Mobile Broadcast Business Management System (MBBMS) is a business management and protection system based on broadcast mobile multimedia which is developed by the China Mobile, and it can use a one-way broadcast network to provide downlink transmission of multimedia content, and it makes use of the authentication management system and the two-way network transmission capacity of the mobile communication network to complete the user authentication, authorization and management; meanwhile, the two-way channel of the mobile communication network is utilized to provide value-added services, such as the interaction and so on, for the mobile users. With the combination of the China Mobile Multimedia Broadcasting (CMMB) and the MBBMS being in operation, the functionality and performance of the terminal processing the code stream in the existing network environment as well as the user experience attract more and more attention.
For the scrambled programs, the terminal must rely on the Entitlement Control Message (ECM) packets in the broadcast code stream to acquire the encrypted key, and the encrypted key is used to obtain the final program stream key via the User Authentication Module (UAM) or the Security Digital (SD) card, thus the scrambled audio and video data can be further descrambled to acquire the raw stream, which is then played to the users for watching, and therefore, the terminal processing the ECM packets is crucial. In the prior art, each ECM packet is analyzed, and each ECM packet generally has two keys (MTKs) for descrambling the audio and video data (one MTK is the current MTK, and the other is the MTK in the next cycle), and the two MTKs in each ECM packet need to be analyzed, which seriously affects the performance of the terminal. Moreover, in the real network, because of the front-end server or the network, there might be error packets in the ECM packets transmitted in the broadcast code stream, and the terminal further acquires the MTK for descrambling and playing according to the ECM packets. If an ECM packet has error, the terminal cannot acquire the key, thus the playing fails, and at this time, the terminal needs to carry out processing reasonably in order to provide the users with a better experience.